1. Field of the Invention
The invention relates generally to methods for designing customized dental restorations and prostheses and particularly dentures. The methods involve taking digital photographs of the patient to be fitted with the restoration or prosthesis and transferring the photographs to a computer software program. The software program uses the photographs to make certain calculations that are translated into their corresponding anterior maxillary tooth mould forms. The program prompts the dental professional to select the desired materials and structure for the denture, such as denture tooth shade, tooth arrangement, patient ridge condition, occlusal scheme, and denture base. This information is used to generate a customized prescription for the denture. The resulting prescription is sent to a dental laboratory that manufactures the denture.
2. Brief Description of the Related Art
Dental professionals use different dental prostheses or appliances to treat patients with lost teeth or tooth structure. By the terms, “prosthesis,” “restoration” “and “appliance” as used herein, it is meant a dental product that replaces or restores lost tooth structure, teeth, or oral tissue including, but not limited to, fillings, inlays, onlays, veneers, crowns, bridges, full dentures, removable partial dentures, relines of full and partial dentures, nightguards, occlusal splints, and the like. Common dental prostheses for full or partially edentulous patients include, for example, full dentures and partial dentures. The dentures are used to restore or replace the lost teeth. In general, removable partial dentures are used to replace some, but not all, of the patient's natural teeth. The partial denture includes a base having a partial set of embedded artificial teeth which rests in the edentulous space and is coupled to abutment teeth by clasps or other connectors. Full dentures, on the other hand, are used to replace all of the patient's natural teeth. A full denture includes a base having a full set of embedded artificial teeth which fits over either the upper gum tissue or lower gum tissue. Partial dentures are designed to preserve any remaining teeth along with hard and soft oral tissue. The dentures must be functional. Furthermore, the denture should enhance the dental and facial aesthetics of the patient. The denture teeth should appear natural. However, it is often difficult to make form-fitting and comfortable dentures. The process is time-consuming requiring the patient to make several dental office visits. In many instance, the dentist must reshape and adjust the denture several times before the patient is satisfied.
Today, a variety of methods are used to make dentures. In one traditional method, a dentist first takes impressions of a patient's dental anatomy. A paste-like material, such as an alginate, is placed in a standard or custom-made impression tray. The dentist inserts the tray in the mouth of a patient and he/she bites down into the tray. Separate impression trays for the upper and lower dental arches are used. The dentist allows the impression material to harden and then removes the trays from the patient's mouth. The hardened impressions are finally sent to a dental laboratory. There, a dental technician prepares models of the upper/lower dental arches by pouring dental stone into the hardened impressions. After a release coating is applied to the dental models, they are placed in a conditioning oven and warmed. A polymerizable resin used to form the baseplate is molded over the warm models. Then, the resin-coated models are placed in a light-curing unit and irradiated with light to harden the baseplate resin. After the light-curing cycle has been completed, the models are removed from the unit and allowed to cool. The hardened baseplates are removed from the respective models. It is customary for the technician to mount wax occlusal rims over the baseplates. The resulting wax rim baseplates are returned to the dentist so they can be evaluated for fit and comfort in the patient's mouth. Then, the completed occlusal registration is articulated.
Next, artificial teeth are built on the processed baseplate and wax rims using a “lost wax” process. In this method, wax is applied to the baseplate and a set of artificial teeth is positioned in the wax. The processed baseplate, with completed tooth arrangement, is placed in a flask containing an investing material. Then, the flask is heated to eliminate the wax. Upon melting, the wax flows out of the flask. Removing the wax from inside of the flask leaves an interior cavity having the shape of the denture. In a next step, a polymerizable acrylic composition is “packed into” into the interior cavity of the flask. The acrylic composition is heated so that it bonds to the teeth and baseplate. When this acrylic composition cures and hardens, it will hold the artificial teeth in position.
Designing and fabricating dentures is a complex process. Many time-consuming steps must be followed to prepare a denture having good aesthetics and mechanical properties. Artificial teeth having the proper color, shade, translucency, length, width, and geometry must be selected and incorporated into the baseplate. The process involves numerous dental professionals including dentists, dental assistants, and laboratory technicians and their work must be carefully coordinated to produce an aesthetically-pleasing and functional denture.
In recent years, computer-based systems using digital images have been developed so that certain dental prostheses can be made more efficiently in a time-saving manner. For example, Lehmann, U.S. Pat. No. 6,786,726 discloses a computer network system for making prostheses such as caps, crowns, bridges, fillings, and the like. In this method, the dental practitioner takes a digital image of the patient's tooth (resulting in a real image). A reference tooth shade (resulting in a reference image) image is also taken. The real and reference images are correlated to find a composite match number having an associated shade. The images are forwarded via computer network to a dental laboratory giving a dental technician access to the images. This allows both the dentist and technician to have simultaneous access to the images—they are able to evaluate the patient's case and develop a treatment plan together using the interactive network.
Jelonek, U.S. Pat. No. 7,035,702 discloses a method for making dental restorations involving the steps of determining the geometrical and aesthetic constraints of the restoration. These constraints are inputted into a computer to mathematically select a recipe for producing the dental restoration. A database of materials and procedures for preparing the dental restoration is compiled. Then, a recipe for making the restoration is produced from the database based on inputted data.
Taub, U.S. Pat. No. 7,33,874 discloses methods for designing and producing dental prostheses using a communication network between a dental clinic and dental laboratory. The system also includes a dental service center which is a separate entity from the dental laboratory. The service center generates a virtual 3D model of the patient's dentition from data obtained by scanning the teeth directly or by scanning a physical model of the teeth. The manufacturing of the prosthesis is shared between the service center and dental lab. The clinic sends instructions to the dental laboratory and service center. In one example, the data needed to produce the virtual 3D model is transmitted from the dental clinic or laboratory to the dental service center. A prescription specifying the teeth that are to be moved in the dental treatment as well as the final position of the teeth is sent to the service center. Then, the service center uses software to make a virtual 3D model, which is used to determine the dental appliance needed. Finally, this information is sent to the dental lab which makes the appliance.
The above-described systems may provide some advantages, but they are not used for designing and making dentures for edentulous patients, which present particular problems. As described above, in a conventional denture-making process, the dentist must manually measure the facial and oral dimensions of the patient, and selects artificial tooth colors, shades, and dimensions using manual tools such as tooth indicators, shade guides, and mould guides. Based on this information, the dentist sends a prescription for the denture to a dental laboratory. There are many variables to this process and the resulting prescription for the denture depends upon the techniques, skills, and experience level of the dental professionals. Some prescriptions will provide detailed information about the requested denture including patient's dental anatomy, baseplate materials, tooth dimensions and shapes, tooth color and shades, and the like. Other prescriptions will simply request the denture be made as the laboratory sees fit and will only provide information on the tooth shade.
The methods and system of the present invention provides the dental professional with a new chair-side method for writing denture prescriptions. The dentist can use the system to generate detailed digital prescriptions including information on facial dimensions of the patient, tooth length, width and geometry, requested composition of the artificial teeth, edentulous ridge condition and occlusal registration of the patient, denture base materials, and color and shade of the artificial teeth. The resulting prescription can be sent by e-mail, paper mail, or facsimile to a dental laboratory that will manufacture the denture. This system is easy-to-use, consistent, and time-saving for the dentist.